Washington (CNN) -- The Department of Defense inspector general is investigating whether medical tests on wounded U.S. military personnel may have violated government rules on human experiments.

The research focused on traumatic brain injuries and whether an over-the-counter dietary supplement might be a possible treatment. The number of brain injuries from improvised explosive devices and other battlefield blasts has soared in recent years in fighting in Iraq and Afghanistan.

The Boston Globe first reported the investigation on Tuesday.

Tests were conducted on approximately 80 service members, according to Maj. Tanya Bradsher, a Pentagon spokeswoman. Researchers were examining the effectiveness of an antioxidant called n-Acetylcysteine for treating mild traumatic brain injury, Bradsher said via e-mail.

A complaint was received in May last year and concerned "suspected research misconduct by a U.S. Navy captain and physician who had served in Iraq," according to Bradsher.

The supplement is available at drugstores and online and according to advertisements has a variety of uses, including treatment of Tylenol overdoses.

A brief mention of the investigation is made in a report about various inspector general investigations that is posted on the inspector general's website. According to the report, a tip prompted the investigation.

"The overall objective is to review the allegations made to the Defense hot line concerning traumatic brain injury research integrity in Iraq," the report said.

"Specifically, DoD OIG [Department of Defense Office of the Inspector General] will determine whether DoD guidance regarding the performance of research on human subjects was violated, and whether research misconduct occurred in a DoD approved clinical research trial evaluating the treatment of mild traumatic brain injury."

Jennifer Plozai of the inspector general's office said by telephone that the investigation is still under way.